"After careful study I have concluded that the report is fundamentally and irretrievably flawed," Ramaphosa told reporters, adding that he has "decided to seek an urgent judicial review" of the findings concerning a controversial 500,000 rand ($36,000) donation.

The country's ombudswoman, Busisiwe Mkhwebane, said in an explosive report on Friday that Ramaphosa "deliberately misled the National Assembly" when he responded to an opposition question in parliament last November.

Ramaphosa initially told lawmakers that the payment was to his son Andile for consultancy work for Bosasa, now known as African Global Operations (AGO).

But he later said it was a donation towards his campaign to become African National Congress party leader -- a hard-fought battle in which he beat ex-president Jacob Zuma's chosen candidate.

He apologised saying he had been misinformed when he first answered the question.

Despite the correction, Mkhwebane said Ramaphosa "indeed misled parliament" and that he should not have rushed to answer the question without having all the facts in hand.

Ramaphosa said the allegations against him by the Public Protector -- or ombudswoman -- "are serious... and should not be taken lightly".

But the report "contains numerous factual inaccuracies of a material nature", he said.

"The findings are wrong in law, are irrational and, in some instances, exceed the scope of the powers of the Public Protector," he said.

"Given these deficiencies ... it is appropriate that the courts make a final and impartial determination on this matter".

'Irrational and wrong in law'

Ramaphosa, who is just two months into a new term since the May elections, said he wanted "an expedited review process so that we do not keep the country in limbo about these matters".

He stressed that the decision to turn to the courts should not be seen as judging the competence of the ombudswoman or her motives "but is motivated instead by a determination that the law should be applied correctly and consistently".

Critics of the ombudswoman accuse her of dabbling in ANC factional battles.

But Ramaphosa said he would not be distracted.

"I want to continue doing the work that I was elected for, and indeed this matter should never be a distraction," he said.

Analysts suggest that damning allegations could boost Ramaphosa's opponents within the ANC, which is riven by infighting.

Ramaphosa replaced the graft-tainted Zuma on promises to fight corruption.

But the party of Nelson Mandela is now bitterly split between Zuma supporters and those backing Ramaphosa, who took the helm after Zuma became entangled in a series of corruption scandals.

The former president faces an inquiry into corruption during his nine-year rule.

On Friday Zuma withdrew from testifying in the inquiry, complaining of bias, but agreed to return at a future date.